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Biomedical subjects

C H Chang

Publications and source records attributed to C H Chang.

At least 307 records · Page 17Linked to original sources
PubMed1995

B7-1 expression of Langerhans cells is up-regulated by proinflammatory cytokines, and is down-regulated by interferon-gamma or by interleukin-10.

Langerhans cells (LC) act as potent antigen-presenting cells (APC) for primary and secondary T cell-dependent immune responses. LC express several costimulatory and/or adhesion molecules such as B7/BB1, which has been implicated as one of the important determinants for professional APC. Recent studies have shown that B7/BB1 antigens comprise three distinct molecules termed B7-1, B7-2, and B7-3. We have examined the regulatory properties of B7-1 expression in LC using various cytokines including interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-10, interferon (IFN)-gamma, granulocyte/macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-alpha. We have demonstrated: 1) that the B7-1 expression of LC is reproducibly up-regulated by either GM-CSF, TNF-alpha, IL-1 alpha, IL-1 beta, or IL-4 in a dose- and time-dependent manner, 2) that GM-CSF exhibits the most active effect on B7-1 up-regulation in each experiment, 3) that IFN-gamma or IL-10 profoundly inhibits the B7-1 expression of LC in a dose- and time-dependent manner, and 4) that the down-regulatory ability of IFN-gamma or IL-10 neutralizes the activity of up-regulatory cytokines. The enhancing or inhibitory action of these cytokines on B7-1 expression occurs selectively because none of the cytokines consistently affects I-A expression of LC. These data suggest that the B7-1 expression of LC may be dynamically regulated by these up- and down-regulatory cytokines in normal and inflammatory epidermal microenvironment.

Animals↗
PubMed1995

Nitric oxide and ventilatory response to hypoxia.

It is believed that hypoxia results in the release of neurotransmitters in the central nervous system, which can excite or inhibit breathing. Recent evidence indicates that nitric oxide (NO) is a physiological messenger molecule that may serve as a neurotransmitter in the CNS. In this study we examined (1) the localization of nitric oxide synthase (NOS) within the nucleus tractus solitarius, and (2) the role of the NO-cGMP pathway in the respiratory response to oxygen deprivation. Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry was used to determine the distribution of neurons that express NOS, an enzyme involved in NO formation. The NOS inhibitor N omega-nitro-L-arginine was used as tool to assess the NOS activity in the medulla, and to define the role of NO in the respiratory response to acute oxygen deprivation. In the rat and the cat brainstem, histochemical studies showed the presence of NADPH-diaphorase reactive neurons within subnuclei of the nucleus tractus solitarius which receive peripheral chemoreceptor inputs. Chronic pretreatment of rats with N omega-nitro-L-arginine (75 mg/kg, ip, twice daily for 7 days) caused a significant decrease in cGMP, and attenuated the ventilatory response to hypoxia. In anesthetized, paralyzed, vagotomized and artificially ventilated cats with intact carotid sinus nerves (n = 8), administration of N omega-nitro-L-arginine (30-100 mg/kg) attenuated the response to hypoxia, and caused the hypoxia induced roll-off of phrenic nerve activity to occur significantly earlier than when NOS activity was not inhibited. In sinoaortic denervated cats (n=9) blockage of NOS potentiated the decline of the phrenic nerve output. The data suggest that oxygen deprivation leads to activation of NO-cGMP pathway in the central nervous system, which contributes to the induction and maintenance of hypoxia-induced increase in respiratory output. In addition, these findings indicate that NO may inhibit inhibitory synaptic transmission that is triggered by CNS hypoxia, and this is not directly related to peripheral chemoreceptor inputs.

Animals↗
PubMed1995

Ipsilateral post-cast hypertrichosis and dyshidrotic dermatitis.

Post-cast hypertrichosis and dyshidrotic dermatitis are not uncommon separately. Yet, the simultaneous occurrence of both conditions in an individual is rare. A patient with both localized hypertrichosis and ipsilateral dyshidrotic dermatitis following multiple fractures and cast application is reported. The clinical presentation, management, spontaneous resolution, and/or response to therapy of post-cast hypertrichosis and dyshidrotic dermatitis that occurred concurrently in an individual were similar to that described when these conditions occur independently. The acquired conditions that may be associated with localized hypertrichosis are summarized and the postulated mechanisms of pathogenesis for dyshidrotic dermatitis are reviewed. The diagnosis of post-cast hypertrichosis in this patient was suspected based upon the distribution and temporal association of the hypertrichosis to the location and placement of his cast, and confirmed by excluding other causes of acquired localized hypertrichosis. Also, the possibility that in this individual either the trauma to his bones, the cast on his arm, or both had an etiologic role in promoting the development of dyshidrotic dermatitis is suggested.

Adrenal Cortex Hormones↗
PubMed1995

Endothelium-dependent contraction of canine coronary artery is enhanced by crystalloid cardioplegic solution.

Experiments were designed to determine whether hyperkalemic crystalloid cardioplegic solution enhances endothelium-dependent contraction of coronary arteries. Segments of canine coronary arteries (n = 8 in each group) were preserved in cold (4 degrees C) crystalloid cardioplegic solution (group 1) and physiologic solution (group 2) for 60 minutes. Segments of preserved and control (group 3) coronary arteries with or without endothelium were suspended in organ chambers to measure isometric force. Perfusate hypoxia (oxygen tension 35 +/- 5 mm Hg) caused endothelium-dependent contraction in the arteries of all three groups. However, vascular segments with endothelium of group 1 exhibited hypoxic contraction (68.5% +/- 15.3% of the initial tension contracted by prostaglandin F2 alpha 2 x 10(-6) mol/L, p < 0.05) that was significantly greater than contraction of the group 2 and group 3 segments with endothelium (26.6% +/- 5.6% and 20.6 +/- 4.4%). The hypoxic contraction in arteries of group 1 could be attenuated by NG-monomethyl-L-arginine, the blocker of endothelial cell synthesis of the nitric oxide from L-arginine. The action of NG-monomethyl-L-arginine could be reversed by L-arginine but not D-arginine. Thus after preservation with cardioplegic solution, augmented endothelium-dependent contraction, occurs by L-arginine-dependent pathway, would favor coronary vasospasm after cardiac operation.

Animals↗
PubMed1995

Differentiation between adenomyoma and leiomyoma with transvaginal ultrasonography.

The clinical utility of transvaginal ultrasonography in the differentiation of adenomyoma from leiomyoma was evaluated in 147 patients who had been scheduled for surgery due to symptomatic uterine masses. In all subjects, ultrasonographic images obtained preoperatively were correlated postoperatively with surgicopathological findings. Pathological findings showed that 110 patients proved to have fibroids, while 30 had adenomyomata. For the diagnosis of adenomyoma, transvaginal ultrasonography attained a sensitivity of 80%, a specificity of 94.3%, a positive predictive value of 85.7% and a negative predictive value of 90.9%, compared with a sensitivity of 94.3%, a specificity of 80%, a positive predictive value of 90.9% and a negative predictive value of 85.7% for leiomyoma diagnosis. Further to assess which characteristic used in ultrasonography was useful in the differential diagnosis, five characteristics were analyzed and compared by chi 2 test. These were position, number, margin and echogenicity of the uterine masses and the presence or absence of hypoechoic spaces (lacunae). Margin, echogenicity, mass number and lacunae were significantly different between both conditions. A stepwise logistic regression procedure revealed that margin, lacunae and echogenicity were good parameters for differentiating adenomyoma from leiomyoma. If we selected the features of distinct margin and absence of hypoechoic lacunae within the masses for analysis, leiomyoma could be correctly predicted in 97% of patients.

Adenomyoma↗
PubMed1995

CIITA activates the expression of MHC class II genes in mouse T cells.

It has long been a puzzle that MHC class II molecules are expressed in human T cells after activation but not in mouse T cells; this expression is believed to play a role in the cell mediated immune response. Recently the MHC class II transactivator (CIITA) has been reported to be a major regulatory factor for both the constitutive and IFN inducible expression of MHC class II genes. Here we show that human T cells expressing MHC class II have CIITA transcripts while MHC class II-negative human T cells and mouse T cells do not. The expression of MHC class II genes in mouse T cells can be reconstituted upon transfection with the human CIITA cDNA. These data indicate that the expression of CIITA explains the expression or lack of expression of MHC class II in human and mouse T cells respectively.

Animals↗
PubMed1995

Hand-held electronic area planimeter.

The focus of this paper is to describe the development and fabrication of a portable hand-held electronic area planimeter to measure wheal areas during dermatitis assays. The planimeter straddles over the wheal and the scientist traces the wheal's perimeter using an optical beam splitter/cross-hair and a miniature x-y table. Transducers connected to the x-y table and an electronic circuit performs the area integration and displays the data on a digital panel meter. The apparatus permits noncontact measurement of areas up to 1000 mm2 with a resolution of 1 mm2.

Animals↗
PubMed1995

Photodamage and skin cancer among paraquat workers.

BACKGROUND: Some workers in paraquat manufacturing, exposed to bipyridines, have developed pigmentation and keratosis on sun-exposed skin. This condition has been described as skin-malignancy or premalignancy. This study was designed to clarify the pathologic features of these lesions and to explore the etiologic role played by bipyridine. METHODS: Twenty-three biopsy specimens, obtained from the affected skin of 10 workers, were scrutinized by a dermatopathologist. A total of 242 exposed workers from 28 paraquat factories were examined and interviewed during the period from 1983 to 1991. The severity of the characteristic skin lesions was graded from the lowest to the highest response to analyze the data by Mantel extension for a trend that focused on the heavy exposure to bipyridines as risk factor. RESULTS: All pathology specimens showed various degrees of solar damage: early actinic change, solar lentigo, actinic keratosis (AK), AK coexisting with squamous cell carcinoma (scc), and scc. Six specimens from four workers were scc or scc in situ. Three of six scc showed the coexistence of AK. Of the workers, 133 had skin lesions ranging in severity from grade 1 to grade 3 on sun-exposed areas. The severity of skin changes is strongly associated with heavy exposure to bipyridines (P < 0.0001). CONCLUSION: This pathologic study proves that all the lesions showed either photodamage or skin cancer. The strong trend in the correlation between severity of photodamage and exposure to bipyridine leads to the speculation about the synergistic role of bipyridine exposure and the solar effect in causing these malignant and premalignant skin lesions.

Adult↗
PubMed1995

Angiotensin IV receptors and signaling in opossum kidney cells.

The pharmacological properties and signaling of angiotensin IV (ANG IV) receptors were studied in opossum kidney cell line OK7A. Saturation binding experiments with 125I-labeled ANG IV demonstrated the presence of high-affinity ANG IV binding sites in OK7A cell membranes with a dissociation constant (Kd) of 0.40 +/- 0.08 nM and a maximal amount of binding sites (Bmax) of 180 +/- 50 fmol/mg protein. In competition experiments, unlabeled ANG IV inhibited 125I-ANG IV binding biphasically: 20% of binding sites had high affinity [inhibition constant (Ki) = 0.44 +/- 0.04 nM] and 80% had low affinity (Ki = 130 +/- 10 nM). ANG III displaced 125I-ANG IV from binding sites with low affinity (Ki = 205 +/- 10 nM), and ANG II did not compete with 125I-ANG IV at concentrations up to 10 microM. The binding of ANG IV to OK7A cell membranes was significantly enhanced in the presence of 5 mM EDTA and completely blocked by 5 mM dithiothreitol. Guanosine 5'-O-(3-thiotriphosphate) inhibited the binding of 125I-ANG IV, indicating the G protein coupling of ANG IV receptors in OK7A cells. In signaling studies, ANG IV induced transient increase in intracellular calcium concentration ([Ca2+]i) from 49 +/- 3 to 280 +/- 45 nM. ANG IV failed to influence phosphoinositol metabolism, indicating that Ca2+ mobilization is not linked to ANG IV signaling. Ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid completely abolished ANG IV-induced increase in [Ca2+]i, consistent with Ca2+ influx. The voltage-sensitive Ca2+ channel blocking agents verapamil and nifedipine attenuated the effect of ANG IV on [Ca2+]i to 133 +/- 33 and 174 +/- 32 nM, respectively. These data suggest that ANG IV induces Ca2+ influx in OK7A cells, at least partially, through the voltage-sensitive Ca2+ channels.

Angiotensin II↗
PubMed1995

Mutational inactivation of the catalytic domain of guanylate cyclase-A receptor.

Guanylate cyclase-A, the receptor for atrial natriuretic factor, contains a protein kinase-like domain and a catalytic domain in the intracellular region. To investigate the active site (the catalytic cavity) of guanylate cyclase-A, we amplified the catalytic domain plus three amino acids from the kinase-like domain of guanylate cyclase-A (GC-c) with polymerase chain reaction (PCR) and expressed it in Escherichia coli. During the screening of the PCR-cloned gene products with guanylate cyclase assay, a mutant that lacks enzyme activity was identified. Results of cDNA sequencing revealed that Leu 817 was replaced by an Arg residue in the mutated protein. The mutated GC-c bound to GTP-agarose as well as the wild-type protein, indicating that the binding capability of mutated GC-c to GTP is not significantly affected by the Arg substitution. Gel-filtration column chromatography showed that, like the wild-type GC-c, the mutated protein also formed a high-molecular-weight complex. Since mutation of Leu 817 to Arg abolishes the catalytic activity, Leu 817 is likely located near the active site of guanylate cyclase-A. These results demonstrate that the carboxyl fragment of guanylate cyclase-A is an ideal system for studying the active site of guanylate cyclase-A.

Adenylyl Cyclases↗
PubMed1995

Activity of a novel nonpeptidyl growth hormone secretagogue, L-700,653, in swine.

L-700,653 is a potent nonpeptidyl GH secretagogue consisting of a benzolactam structure: (4'-[[3(R)-[[3-[(2(S),3-dihydroxypropyl) amino]3-methyl-1-oxobutyl]amino]2,3,4,5-tetrahydro-2-oxo-1H-1-benzaze pin- 1-yl]methyl][1,1'-biphenyl]2-carboxamide hydrochloride). When administered sc by a Medi-Jector device at 0, 0.003, 0.01, 0.03, and 0.1 mg/kg BW to male castrated swine (approximately 50 kg BW), L-700,653 stimulated dose-related increases in peak plasma GH concentrations by 20% (P = NS), 150% (P = NS), 250% (P < 0.05), and 340% (P < 0.05), respectively, over the saline vehicle control value (11.3 +/- 6.5 ng/ml) and stimulated increases in GH areas under the curve (AUCs) by 10% (P = NS), 30% (P = NS), 90% (P < 0.05), and 100% (P < 0.01), respectively, over the saline vehicle control value (799 +/- 145 ng/min.ml). After sc administration of L-700, 653, there were no significant changes in plasma LH levels. Subcutaneous dose of 0.03 or 0.1 mg/kg increased plasma cortisol AUCs by 60% (P = NS) and 150% (P < 0.03) over the control value (2461 +/- 935 ng/min.ml) and increased cortisol peaks by 80% (P = NS) and 200% (P < 0.01), respectively, over the control value (38.3 +/- 12.3 ng/ml). Repeated sc administration of L-700,653 (0.03 or 0.1 mg/kg) at 0800, 1400, and 2000 h daily over 3 days consistently increased mean GH peak and GH AUC at each treatment period, with minimal and maximal increases of 40% and 190% in GH peak level at the 0.03 mg/kg dose and 100% and 400% increases in GH peak level at the 0.01 mg/kg dose, respectively. Continuous i.v. infusion of L-700,653, at either 0.01 or 0.1 mg/kg BW.h over a 180-min period, increased GH AUCs by 60% (P = NS) or 470% (P < 0.01) and GH peaks by 190% (P = NS) or 1520% (P < 0.01), respectively, over the control value (589 +/- 313 ng/min.ml; 7.0 +/- 11.1 ng/ml). After a 180- to 300-min saline infusion, an iv bolus dose of 0.1 mg/kg L-700,653 resulted in GH responses inversely proportional to the previous infusion dose, i.e. 0, 0.01, or 0.1 mg/kg.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Application of thoracoscopy for lung metastases.

Lung nodules in patients with a history of malignancy usually require tissue diagnosis that will provide prognostic information and dictate further therapy. Patients with a favorable tumor histologic condition and limited tumor burden were often considered for resection. This is usually accomplished by wedge resection through open thoracotomy when the lesions were peripheral. However, complications related to open thoracotomy often exclude poor-risk patients, especially those with impaired pulmonary function. Currently, technique of thoracoscopic resection is opening up new vistas and unimagined options for the thoracic surgeon in the management of pulmonary diseases. With the application of thoracoscopy and small incisions, it is now possible for the thoracic cavity and its contained organs to be thoroughly explored. Our recent experience with the thoracoscopic resection as a primary treatment for lung metastases is the focus of this report. Forty-seven patients with a history of malignancy and new lung metastases underwent this type of resection. Postoperatively, there is less pain, quick functional recovery, and excellent cosmetic healing. It is a safe and promising approach.

Female↗
PubMed1995

Thoracoscopic surgery as a routine procedure for spontaneous pneumothorax. Results from 82 patients.

A total of 82 consecutive patients with recurrent or persistent spontaneous pneumothorax were considered for thoracoscopic blebectomy or bullectomy and pleurodesis. The median age was 47 years, and 70% were men. All the patients were successfully treated using a video-assisted thoracoscopic technique. There were no deaths attributable to the procedure. Complications occurred in 6 patients (7.3%). Three patients (4%) with diffuse bullous lung disease had prolonged intubation (9, 11, and 12 days, respectively). Persistent air leaks lasting from 10 to 14 days occurred in 2 patients (3%). One patient had an endoloop slip from the lung parenchyma after a forceful sneeze 2 days after the operation. Air leak subsided after the second operation using a conventional suturing technique. Blebs or bullae were present in 69 patients (83%). These were ablated by endoscopic stapling (37 patients) and through thoracoscopic ligation using an endoloop technique (32 patients). In this group of patients, the median postoperative hospital stay was 5 days. Thirteen patients with air leaks and diffuse bullous lung disease received only talc insufflation thoracoscopically. All of them showed good lung expansion after the operation. There are no recurrences, with a mean follow-up of 22 months. These results suggest that thoracoscopic ablation of blebs or bullae and pleurodesis may be applicable to patients with spontaneous pneumothorax who require surgical intervention.

Adolescent↗
PubMed1995

Thoracoscopic-assisted lobectomy. Preliminary experience and results.

A preliminary report is made on the use of videothoracoscopy to achieve pulmonary lobectomy in 16 patients, including 12 with centrally located pulmonary metastases and 4 with benign lesions (3 bronchiectases and 1 endobronchial hamartoma). Videothoracoscopy was performed on eight right-lower lobes, one middle lobe, two right-upper lobes, four left-lower lobes, and one left-upper lobe with a thoracoscope and conventional thoracic instruments. All patients received standard pulmonary lobe resection with lymph node clearance similar to that achieved with open thoracotomy. The mean operative time was 3 h (range, 2.5 to 4 h). Average blood loss was 100 mL and mean length of hospital stay was 6 days (range, 4 to 8 days). A combination of videothoracoscopy with use of conventional instruments resulted in similar performance but less chest wall interruption than in conventional pulmonary lobectomy. Videothoracoscopy showed safer and faster lung resection, which subsequently minimized the perioperative morbidity. Pain intensity was lessened, functional recovery was quicker, and hospital stays were shorter in the patients we reviewed.

Adult↗
PubMed1995

Aortic dissection in Taiwan.

We retrospectively reviewed all patients with a final diagnosis of spontaneous thoracic aortic dissection treated at Linkou Chang Gung Memorial Hospital between January 1989 and December 1994. There were a total of 109 patients with a mean age of 55 +/- 11 years ranging from 19 to 88 years. The male-to-female ratio was 2 to 1 (73 to 36). There was a predilection to present during the colder months, with 69% seen between September 1 and February 28 and only 31% during the warmer half of the year. In most patients, hypertension (85%) was the major predisposing factor with another 7% having Marfan syndrome. The remaining 8% had no obvious underlying disease except for one patient who had an atrial septum defect. Presenting chief complaints in order of frequency included: anterior chest pain 58.7% (64/109), back pain 19.2% (21/109), abdominal pain 10.1% (11/109), consciousness change 3.7% (4/109), neck pain 2.7% (3/109), paraparesis 2.7% (3/109), dyspnea 1.8% (2/109), and hemoptysis 0.9% (1/109). The diagnostic breakdown revealed 46% to be type A (50/109) and 54% type B (59/109). A total of 26 (24%) patients died in hospital (16% were type A and 8% were type B). (Type A included all proximal dissections and those distal dissections that extend retrograde to involve the arch and ascending aorta; Type B refers to the other distal dissections without proximal extension; proposed by Daily et al.) Thoracic aortic dissection remains an important concern in patients with a history of hypertension. Patients seem particularly susceptible during cold weather months. The average age of our patients was only 55 years and 24% of them died during hospitalization. Earlier identification and more aggressive antihypertensive treatment is required.

Adult↗
PubMed1995

Using a titanium mesh plate to reconstruct the orbital floor after an incompletely reduced zygomaticomaxillary complex fracture.

A 30 year-old male came to us for correcting his severe left enophthalmos five months after a facial trauma in a traffic accident. CT scan of his left orbit showed a greatly increased orbital volume, which was resulted from the incomplete reduction of left zygomaticomaxillary complex (ZMC) fracture, unrepaired medial and lateral walls, and improper restoration of the orbital floor with a silicone sheet. Also, the decreased ocular volume, due to the evisceration of the ruptured eyeball with intraocular silicone ball implantation, contributed to the patient's enophthalmos. Because the patient refused any kind of osteotomy for his incompletely reduced and malunion ZMC fracture in the procedures of orbital reconstruction, correction of his severe enophthalmos became very difficult if not impossible. Therefore, we used a piece of titanium mesh plate about 2.5 x 4 cm in size, and folded it into an L shape. The shorter part of the L-shaped plate was used to fix the whole plate by screwing it into the anterior surface of the inferior orbital rim. The longer part of the plate was used as a new orbital floor. To hold and push the intraocular implant upward and anteriorly, the longer part of the plate was adjusted to a level higher than the original floor level, and was bent upward gently in the posterior part. Postoperatively, the severe enophthalmos was markedly improved, and the patient was satisfied although an evident supratarsal sulcus was still present. After a follow-up of 18 months, no complication of migration, infection, or extrusion of the titanium mesh plate occurred.

Adult↗
PubMed1995

Cytotoxicity of intracameral injection drugs to corneal endothelium as evaluated by corneal endothelial cell culture.

The cell culture method was used to quantitatively evaluate the cytotoxicity to porcine corneal endothelial cells by drugs in the usual concentrations of intracameral injections (ICI). Time-dependent cytotoxicity of drugs was evaluated quantitatively; dye exclusion assay by trypan blue was used as a viability assay; and cytotoxicity to corneal endothelium was tested using amphotericin-B, amikacin, colistin, sulbenicillin, and cephradine in their original, 10-fold, and 100-fold ICI concentrations. Original and 10-fold ICI concentrations of betamethasone also were used. In original and 10-fold ICI concentrations, only amphotericin-B had significant cytotoxicity. In 100-fold ICI concentrations, amphotericin-B, colistin, and sulbenicillin had significant cytotoxicity. Betamethasone had neither a cytotoxic nor a proliferative effect in its original and 10-fold ICI concentrations. A 0.1-fold ICI concentration of amphotericin-B also showed 42.75% cytotoxicity to corneal endothelium by monolayer cultured cells and the time-dependent cytotoxicity of drugs as a quantitative method is efficient and objective.

Animals↗